## Type of Work

Article (48) Book (0) Theses (10) Multimedia (0)

## Peer Review

Peer-reviewed only (50)

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## Campus

UC Berkeley (9) UC Davis (2) UC Irvine (13) UCLA (15) UC Merced (4) UC Riverside (5) UC San Diego (5) UCSF (7) UC Santa Barbara (0) UC Santa Cruz (3) UC Office of the President (2) Lawrence Berkeley National Laboratory (5) UC Agriculture & Natural Resources (1)

## Department

Center for Embedded Network Sensing (4) Department of Earth System Science (2) Institute of Governmental Studies (2) Research Grants Program Office (RGPO) (2) Center for Medieval and Renaissance Studies (1) Department of Emergency Medicine (UCI) (1)

## Journal

California Journal of Politics and Policy (2) Comitatus: A Journal of Medieval and Renaissance Studies (1) Electronic Green Journal (1) Proceedings of the Vertebrate Pest Conference (1) UCLA Journal of Environmental Law and Policy (1) Western Journal of Emergency Medicine: Integrating Emergency Care with Population Health (1)

## Discipline

Life Sciences (2) Medicine and Health Sciences (2)

## Reuse License

BY - Attribution required (8) BY-ND - Attribution; No derivatives (1) BY-SA - Attribution; Derivatives must use same license (1)

## Scholarly Works (58 results)

The power of magnetic resonance imaging (MRI) is its ability to image the internal structure of optically opaque samples and provide detailed maps of a variety of important parameters, such as density, diffusion, velocity and temperature. However, one of the fundamental limitations of this technique is its inherent low sensitivity. For example, the low signal to noise ratio (SNR) is particularly problematic for imaging gases in porous materials due to the low density of the gas and the large volume occluded by the porous material. This is unfortunate, as many industrially relevant chemical reactions take place at gas-surface interfaces in porous media, such as packed catalyst beds. Because of this severe SNR problem, many techniques have been developed to directly increase the signal strength. These techniques work by manipulating the nuclear spin populations to produce polarized} (i.e., non-equilibrium) states with resulting signal strengths that are orders of magnitude larger than those available at thermal equilibrium. This dissertation is concerned with an extension of a polarization technique based on the properties of parahydrogen. Specifically, I report on the novel use of heterogeneous catalysis to produce parahydrogen induced polarization and applications of this new technique to gas phase MRI and the characterization of micro-reactors. First, I provide an overview of nuclear magnetic resonance (NMR) and how parahydrogen is used to improve the SNR of the NMR signal. I then present experimental results demonstrating that it is possible to use heterogeneous catalysis to produce parahydrogen-induced polarization. These results are extended to imaging void spaces using a parahydrogen polarized gas. In the second half of this dissertation, I demonstrate the use of parahydrogen-polarized gas-phase MRI for characterizing catalytic microreactors. Specifically, I show how the improved SNR allows one to map parameters important for characterizing the heat and mass transport in a heterogeneous catalyst bed. This is followed by appendices containing detailed information regarding the design and use of my experimental setup.

This thesis is concerned with the mixed Tate property of reductive algebraic groups G, which in particular guarantees a Chow Kunneth property for the classifying space BG. Toward this goal, we first refine the construction of the compactly supported motive of a quotient stack.

In the first section, we construct the compactly supported motive M^c(X) of an algebraic space X and demonstrate that it satisfies expected properties, following closely Voevodsky's work in the case of schemes.

In the second section, we construct a functorial version of Totaro's definition of the compactly supported motive M^c([X/G]) for any quotient stack [X/G] where X is an algebraic space and G is an affine group scheme acting on it. A consequence of functoriality is a localization triangle for these motives.

In the third section, we study the mixed Tate property for the classical groups as well as the exceptional group G_2. For these groups, we demonstrate that all split forms satisfy the mixed Tate property, while exhibiting non-split forms that do not. Finally, we prove that for any affine group scheme G and normal split unipotent subgroup J of G, the motives M^c(BG) and M^c(B(G/J)) are isomorphic.

We present a search for a simplified supersymmetric model with pair-produced light supersymmetric bottom quarks decaying to neutralinos. Higgs-type neutralinos (Higgsinos) decay to the Higgs boson and LSP, with at least one Higgs bo son decaying to a diphoton system. Events with at least two $b$-jets and a photon pair in the Higgs-tagged invariant mass window are considered. In $36.2$ $ \textrm{fb}^{-1}$ of proton-proton collision data collected at the CMS experiment at $\sqrt{s} = 13$ TeV, we find no evidence of signal and set lower limits on the production of the bottom squark at a 95\% confidence level at masses of below 350 GeV, with a Higgsino mass of 150 GeV or less.

Using the recent work of Frankland and Spitzweck, we define motivic Steenrod operations

on the mod p motivic cohomology of smooth varieties defined over a base field of characteristic

p. We show that the operations satisfy expected properties such as the Adem relations and

Cartan formula when restricted to mod p Chow groups. Using these new operations, we remove previous

restrictions on the characteristic of the base field for Rost's degree formula. We also prove

Hoffmann's conjecture (generalized to include quadratic forms over a base field of characteristic

2) on the possible values of the first Witt index of an anisotropic quadratic form for the special

case of nonsingular anisotropic quadratic forms over a base field of characteristic 2.